what would you think of havinga basicX microcontroller in place of a Basic Stamp for next year. It is just as easily programmable with a
simple BASIC instruction set . Its is much faster, has greater math capabilitues including signed variables, a real time clock, interrupts 400bytes of ram(as opposed to 26) and built in supporp for trig. It would not requre much in the way of redesigning the Robot controller, in fact i THINK it may be pin for pin compatible with the Basic Stamp.
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here is a comparison with the Basic stamp 2 SX microcontroller
http://www.basicx.com/Products/BX-24/bx24compare.htm